1. Field of the Invention
The present invention relates to a vehicle air conditioner having a first air passage and a second air passage partitioned from each other. The air conditioner can set an inside/outside air double flow mode in which heated high-temperature inside air is blown from a foot air outlet, and low-humidity warm outside air is blown from a defroster air outlet.
2. Related Art
In a conventional vehicle air conditioner, when maximum heating is set in a foot or foot/defroster mode in which air is blown from both a foot air outlet and a defroster air outlet, an inside/outside air double flow mode (hereinafter referred to as inside/outside air mode) is automatically set by a control unit. When the air conditioner is designed to be manually operated by a passenger to reduce its manufacturing cost, the air conditioner needs to have an inside/outside air mode switching lever disposed in an air-conditioning operation panel. The mode switching lever has three air mode positions, that is, an inside air mode, an outside air mode and the inside/outside air mode. The passenger selects one of the three air modes by manual operation.
However, as shown in FIG. 3, when the passenger manually changes from the outside air mode to the inside/outside air mode while an air temperature adjusting lever for adjusting a temperature of conditioned air is set to a middle temperature position (i.e., a middle temperature area in spring and fall), a temperature of air blown from the foot outlet abruptly changes from Tf2 to Tf1, although a position of the air temperature adjusting lever does not change. As a result, a gap .DELTA.T2 between a temperature Td of air blown from the defroster outlet and Tf2 abruptly increases to a gap .DELTA.T1 between Td and Tf1. In FIG. 3, .DELTA.T1 is 21.degree. C. with an outside air temperature of 10.degree. C., an inside air temperature of 25.degree. C. and an average air outlet temperature of 35.degree. C., and .DELTA.T2 is 15.degree. C. with an outside air temperature of 10.degree. C. and an average air outlet temperature of 35.degree. C. Thus, when the outside air mode is changed to the inside/outside air mode by the passenger while outside air has a relatively low temperature, the gap .DELTA.T2 abruptly increases to .DELTA.T1, thereby worsening air conditioning feeling. Further, since the passenger needs to select one from the three air mode positions of the mode switching lever, a manual operation of the air conditioner by the passenger is complicated in comparison with the operation of an air conditioner having an inside/outside air switching lever with only two air mode positions, that is, the inside air mode and the outside air mode.